A generic-type turbine is known for example from GB 1 171 495 A. The turbine in this case is equipped with a partition in the region of the turbine blading, which is radially movable towards the rotor rotational axis in order to adjust the throughput of the mass flow of the working medium during operation of the turbine. A device which is used for the same purpose is known from DE 1 647 673 A. In this case, a ring which is arranged in the axially divided stator blades of a blade ring has a number of openings which corresponds to the number of stator blades. This ring is movable relative to the fixed stator blades in the circumferential direction in order to provide a variable flow cross section for the operating gas by means of a variable overlap of openings of the ring and the free spaces between the stator blades.
The aforementioned gas turbines are flexibly activated or deactivated during operation of the thermal power plant. When “running up” the gas turbine from the deactivated operating state to the load operation a specific load gradient, however, must not be exceeded in order to allow all the components sufficient time to correspondingly warm up in cooperation with the other components. In this way, unacceptably high stresses between the components, which would lead to component failures, are avoided. That is to say, the time period which is required for running up the gas turbine to the load operation must be selected long enough in order to allow sufficient time for the heating-through within the permissible stress states in each case and so as not to cause any damage to the gas turbine.